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1. Expedition 382 summary

Author

Weber, M.E., primary, Raymo, M.E., additional, Peck, V.L., additional, Williams, T., additional, Armbrecht, L.H., additional, Bailey, I., additional, Brachfeld, S.A., additional, Cardillo, F.G., additional, Du, Z., additional, Fauth, G., additional, García, M., additional, Glüder, A., additional, Guitard, M.E., additional, Gutjahr, M., additional, Hemming, S.R., additional, Hernández-Almeida, I., additional, Hoem, F.S., additional, Hwang, J.H., additional, Iizuka, M., additional, Kato, Y., additional, Kenlee, B., additional, Martos, Y.M., additional, O'Connell, S., additional, Perez, L.F., additional, Reilly, B.T., additional, Ronge, T.A., additional, Seki, O., additional, Tauxe, L., additional, Tripathi, S., additional, Warnock, J.P., additional, and Zheng, X., additional

Published
2021
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2. Site U1538

Author

Weber, M.E., primary, Raymo, M.E., additional, Peck, V.L., additional, Williams, T., additional, Armbrecht, L.H., additional, Bailey, I., additional, Brachfeld, S.A., additional, Cardillo, F.G., additional, Du, Z., additional, Fauth, G., additional, García, M., additional, Glüder, A., additional, Guitard, M.E., additional, Gutjahr, M., additional, Hemming, S.R., additional, Hernández-Almeida, I., additional, Hoem, F.S., additional, Hwang, J.H., additional, Iizuka, M., additional, Kato, Y., additional, Kenlee, B., additional, Martos, Y.M., additional, O'Connell, S., additional, Perez, L.F., additional, Reilly, B.T., additional, Ronge, T.A., additional, Seki, O., additional, Tauxe, L., additional, Tripathi, S., additional, Warnock, J.P., additional, and Zheng, X., additional

Published
2021
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3. Expedition 382 methods

Author

Weber, M.E., primary, Raymo, M.E., additional, Peck, V.L., additional, Williams, T., additional, Armbrecht, L.H., additional, Bailey, I., additional, Brachfeld, S.A., additional, Cardillo, F.G., additional, Du, Z., additional, Fauth, G., additional, García, M., additional, Glüder, A., additional, Guitard, M.E., additional, Gutjahr, M., additional, Hemming, S.R., additional, Hernández-Almeida, I., additional, Hoem, F.S., additional, Hwang, J.H., additional, Iizuka, M., additional, Kato, Y., additional, Kenlee, B., additional, Martos, Y.M., additional, O'Connell, S., additional, Perez, L.F., additional, Reilly, B.T., additional, Ronge, T.A., additional, Seki, O., additional, Tauxe, L., additional, Tripathi, S., additional, Warnock, J.P., additional, and Zheng, X., additional

Published
2021
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4. Site U1534

Author

Peck, V.L., primary, Weber, M.E., additional, Raymo, M.E., additional, Williams, T., additional, Armbrecht, L.H., additional, Bailey, I., additional, Brachfeld, S.A., additional, Cardillo, F.G., additional, Du, Z., additional, Fauth, G., additional, García, M., additional, Glüder, A., additional, Guitard, M.E., additional, Gutjahr, M., additional, Hemming, S.R., additional, Hernández-Almeida, I., additional, Hoem, F.S., additional, Hwang, J.H., additional, Iizuka, M., additional, Kato, Y., additional, Kenlee, B., additional, Martos, Y.M., additional, O'Connell, S., additional, Perez, L.F., additional, Reilly, B.T., additional, Ronge, T.A., additional, Seki, O., additional, Tauxe, L., additional, Tripathi, S., additional, Warnock, J.P., additional, and Zheng, X., additional

Published
2021
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5. Ice sheet–free West Antarctica during peak early Oligocene glaciation

Author

Klages, J.P., Hillenbrand, C.-D., Bohaty, S.M., Salzmann, U., Bickert, T., Lohmann, G., Knahl, H.S., Gierz, P., Niu, L., Titschack, J., Kuhn, G., Frederichs, T., Müller, J., Bauersachs, T., Larter, R.D., Hochmuth, K., Ehrmann, W., Nehrke, G., Rodríguez-Tovar, F.J., Schmiedl, G., Spezzaferri, S., Läufer, A., Lisker, F., van de Flierdt, T., Eisenhauer, A., Uenzelmann-Neben, G., Esper, O., Smith, J.A., Pälike, H., Spiegel, C., Dziadek, R., Ronge, T.A., Freudenthal, T., Gohl, K., Klages, J.P., Hillenbrand, C.-D., Bohaty, S.M., Salzmann, U., Bickert, T., Lohmann, G., Knahl, H.S., Gierz, P., Niu, L., Titschack, J., Kuhn, G., Frederichs, T., Müller, J., Bauersachs, T., Larter, R.D., Hochmuth, K., Ehrmann, W., Nehrke, G., Rodríguez-Tovar, F.J., Schmiedl, G., Spezzaferri, S., Läufer, A., Lisker, F., van de Flierdt, T., Eisenhauer, A., Uenzelmann-Neben, G., Esper, O., Smith, J.A., Pälike, H., Spiegel, C., Dziadek, R., Ronge, T.A., Freudenthal, T., and Gohl, K.

Abstract

One of Earth’s most fundamental climate shifts – the greenhouse-icehouse transition 34 Ma ago – initiated Antarctic ice-sheet build-up, influencing global climate until today. However, the extent of the ice sheet during the Early Oligocene Glacial Maximum (~33.7–33.2 Ma) that immediately followed this transition, a critical knowledge gap for assessing feedbacks between permanently glaciated areas and early Cenozoic global climate reorganization, is uncertain. Here, we present shallow-marine drilling data constraining earliest Oligocene environmental conditions on West Antarctica’s Pacific margin – a key region for understanding Antarctic ice sheet-evolution. These data indicate a cool-temperate environment, with mild ocean and air temperatures preventing West Antarctic Ice Sheet formation. Climate-ice sheet modeling corroborates a highly asymmetric Antarctic ice sheet, thereby revealing its differential regional response to past and future climatic change.

Published
2024

7. Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years

Author

Weber, M.E., Bailey, I., Hemming, S.R., Martos, Y.M., Reilly, B.T., Ronge, T.A., Brachfeld, S., Williams, T., Raymo, M., Belt, M., Smik, L., vogel, H., Peck, V., Armbrecht, L., Cage, A., Cardillo, F.G., Du, Z., Fauth, G., Fogwill, C.J., and García-García, M. (Margarita)

Subjects
carbon, carbon cycle, pleistocene, Medio Marino, Centro Oceanográfico de Cádiz, ice ages, antarctic zone
Abstract

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels., SI

Published
2022

8. Episodes of Early Pleistocene West Antarctic Ice Sheet Retreat Recorded by Iceberg Alley Sediments

Author

Bailey, I., Hemming, S., Reilly, B.T., Rollinson, G., Williams, T, Weber, M., Raymo, M.E., Peck, V.L., Ronge, T.A., Brachfeld, S., O'Connell, S., Tauxe, L., Warnock, J.P., Armbrecht, L., Cardillo, F.G., Fauth, G., García-García, Margarita, et al., Bailey, I., Hemming, S., Reilly, B.T., Rollinson, G., Williams, T, Weber, M., Raymo, M.E., Peck, V.L., Ronge, T.A., Brachfeld, S., O'Connell, S., Tauxe, L., Warnock, J.P., Armbrecht, L., Cardillo, F.G., Fauth, G., García-García, Margarita, and et al.

Abstract

Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to examine for this purpose because they receive iceberg-rafted debris (IBRD) sourced from the Pacific- and Atlantic-facing sectors of West Antarctica. Here we report on the sedimentology and provenance of the oldest of three cm-scale coarse-grained layers recovered from this sea at International Ocean Discovery Program Site U1538. These layers are preserved in opal-rich sediments deposited ∼1.2 Ma during a relatively warm regional climate. Our microCT-based analysis of the layer's in-situ fabric confirms its ice-rafted origin. We further infer that it is the product of an intense but short-lived episode of IBRD deposition. Based on the petrography of its sand fraction and the Phanerozoic 40Ar/39Ar ages of hornblende and mica it contains, we conclude that the IBRD it contains was likely sourced from the Weddell Sea and/or Amundsen Sea embayment(s) of West Antarctica. We attribute the high concentrations of IBRD in these layers to “dirty” icebergs calved from the WAIS following its retreat inland from its modern grounding line. These layers also sit at the top of a ∼366-m thick Pliocene and early Pleistocene sequence that is much more dropstone-rich than its overlying sediments. We speculate this fact may reflect that WAIS mass-balance was highly dynamic during the ∼41-kyr (inter)glacial world.

Published
2022

9. Temperate rainforests near the South Pole during peak Cretaceous warmth

Author

Klages, J.P., Salzmann, U., Bickert, T., Hillenbrand, C.-D., Gohl, K., Kuhn, G., Bohaty, S.M., Titschack, J., Müller, J., Frederichs, T., Bauersachs, T., Ehrmann, W., van de Flierdt, T., Pereira, P.S., Larter, R.D., Lohmann, G., Niezgodzki, I., Uenzelmann-Neben, G., Zundel, M., Spiegel, C., Mark, C., Chew, D., Francis, J.E., Nehrke, G., Schwarz, F., Smith, J.A., Freudenthal, T., Esper, O., Pälike, H., Ronge, T.A., Dziadek, R., Afanasyeva, V., Arndt, J.E., Ebermann, B., Gebhardt, C., Hochmuth, K., Küssner, K., Najman, Y., Riefstahl, F., Scheinert, M., PS104, the Science Team of Expedition, and Natural Environment Research Council (NERC)

Subjects
Spores, Geologic Sediments, Rainforest, 010504 meteorology & atmospheric sciences, General Science & Technology, Climate, WEST ANTARCTICA, Antarctic ice sheet, Antarctic Regions, F800, ANTARCTIC ICE-SHEET, 010502 geochemistry & geophysics, BOUNDARY-CONDITIONS, 01 natural sciences, Science Team of Expedition PS104, Temperate climate, JAMES-ROSS-ISLAND, Glacial period, History, Ancient, 0105 earth and related environmental sciences, Carbon dioxide in Earth's atmosphere, Multidisciplinary, Science & Technology, Atmosphere, Fossils, AMUNDSEN SEA EMBAYMENT, Temperature, COEXISTENCE APPROACH, Carbon Dioxide, Models, Theoretical, Cretaceous, Multidisciplinary Sciences, HETEROCYST GLYCOLIPIDS, Science & Technology - Other Topics, PROXY DATA, Pollen, Climate model, Physical geography, Temperate rainforest, MARIE BYRD LAND, Geology, New Zealand
Abstract

The mid-Cretaceous period was one of the warmest intervals of the past 140 million years1–5, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume6. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide. Multi-proxy core data and model simulations support the presence of temperate rainforests near the South Pole during mid-Cretaceous warmth, indicating very high CO2 levels and the absence of Antarctic ice.

Published
2020

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